In a communication system, communication of data is effectuated between at least a pair of communication stations, one communication station forming a sending station and another of the communication stations forming a receiving station. The need to communicate data is regularly a necessary aspect of modern society. And, such need to communicate data shall likely become an even greater necessity in the future.
Different types of communication systems have been developed and have been utilized to communicate data pursuant to different types of communication services. As advancements in communication technologies are made available, such advancements have been implemented in existing communication systems. And, such advancements have permitted the implementation of new types of communication systems. A radio communication system is an exemplary type of communication system. The advancements in communication technologies have, for instance, been implemented in radio communication systems. And, new types of radio communication systems have been made possible as a result of such advancements in communication technologies.
A radio communication system differs with a conventional, wireline communication system in that a radio communication system utilizes radio links upon which to communicate data. More particularly, a communication path that extends between the sending and receiving stations of a radio communication system includes, at least along a portion thereof, a radio link. Radio channels are defined upon the radio link. And, at least for that portion of the communication path, data is communicated upon one or more radio channels. That is to say, a radio link is substituted for a wireline connection. And, when the radio link is substituted for the wireline connection, the need to use a wireline connection along that portion of the communication path is obviated.
Various advantages are provided through the use of a radio communication system. Costs associated with initial installation and initial deployment of a radio communication system are generally less than the corresponding costs of the installation and deployment of a wireline counterpart. And, a radio communication system can be implemented as a mobile communication system. In a mobile communication system, communication mobility is provided. One or more of the communication stations operable in a mobile communication system is mobile, i.e., permitted movement.
A type of mobile communication system that has achieved high levels of usage is a cellular communication system. A cellular communication system includes a network part, referred to as a network infrastructure, with which mobile stations communicate. The network infrastructures of cellular communication systems have been installed to encompass significant portions of the population centers of the world. Voice and, increasingly, data services are effectuated through the use of a cellular communication system. A cellular communication system is typically constructed in conformity with a standard, operational specification. Various cellular communication standards have been promulgated, and cellular communication systems that are operable pursuant to such cellular communication standards have been installed and implemented. Successive generations of communication standards have been promulgated. So-called, first-generation, second-generation, and third-generation communication standards have been promulgated. And, communication systems constructed to be operable in conformity with such communication standards have been installed, implemented, and popularly utilized. Additional, successor-generation standards are under development, and plans to install such systems are proposed.
Fixed-site, base transceiver stations form portions of the network infrastructures of cellular communication systems. The base transceiver stations are positioned at spaced intervals, and each base transeiver station defines a cell. Collectively, the cells together define the geographic area that is encompassed by the cellular communication system. When a mobile station, operable in active communications pursuant to effectuation of a communication service, travels between cells of the communication system, handovers are performed between base transceiver stations to permit continued communications to be carried out. Because communication handovers are performed, the power levels of communication signals that contain the data that is communicated between a mobile station and the network infrastructure are relatively low. And, as a result, the same frequencies can be used, according to a cell reuse scheme, within the communication system. The bandwidth allocated to a cellular communication system is efficiently utilized due to the ability to reuse the channel frequencies.
The mobile stations that are operable in a cellular communication system are formed of radio transceivers, including both transmit parts and receive parts. Mobile stations are packaged in increasingly smaller housings and regularly are of dimensions permitting their hand-carriage by a user. To permit the circuitry of the mobile station to be housed within the housing of such dimensions, the circuitry must correspondingly be of small dimensions. Careful selection of the circuitry of the transmit and receive portions of the mobile station is required so that the transceiver circuitry can be housed within the housing. The receive portions of the mobile station can, for example, be formed of heterodyne or super heterodyne architectures. Generally, such architectures, however, can not be implemented upon a single die and, instead, require the use of external filters. These off-chip components, and matched interfaces needed together therewith, limit the miniaturization permitted of the receive portion and also increase the complexity of the design and implementation of such receive portions.
Direct conversion architectures can instead be used. Direct conversion receivers are advantageous in that a direct conversion receiver is capable of single-chip integration. However, the reception sensitivity of a direct conversion receiver is generally less than that of a super heterodyne receiver that exhibits the same levels of current consumption. Because a direct conversion receiver does not utilize a passive channel filter, such as a SAW filter, to suppress unwanted signals or interference, the overall linearity of a direct conversion receiver is generally weaker than that of a super heterodyne receiver. To compensate for the reduced linearity of a direct conversion receiver, the receiver is sometimes constructed to exhibit reduced reception sensitivity. The reduced reception sensitivity limits the performance of a mobile station that incorporates a direct conversion receiver as the receive portion thereof.
If a manner could be found by which to provide an enhanced, direct conversion receiver architecture that provides higher reception sensitivity, without power consumption increase, and an improved capability to avoid high-interference jamming, improved communication performance of a direct conversion receiver would be provided. When implemented as part of a mobile station operable in a cellular, or other mobile, communication system, improved communication performance of the mobile station would correspondingly also be provided.
It is in light of this background information related to communications in a cellular, or other radio, communication system that the significant improvements of the present invention have evolved.